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freebsd-skq/lib/libutil/realhostname.3

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Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
1999-04-06 23:02:35 +00:00
.\" Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
$Id$ -> $FreeBSD$
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.\" $FreeBSD$
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.\"
.Dd April 6, 1999
.Dt REALHOSTNAME 3
mdoc: order prologue macros consistently by Dd/Dt/Os Although groff_mdoc(7) gives another impression, this is the ordering most widely used and also required by mdocml/mandoc. Reviewed by: ru Approved by: philip, ed (mentors)
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.Os
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Sh NAME
.Nm realhostname
.Nd "convert an IP number to the real host name"
Introduce .Lb macro to libutil manpages Sort .Nm values in some manpages Remove explicit note about compiling with -lutil, it's implicitly declared by .Lb macro now.
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.Sh LIBRARY
.Lb libutil
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Sh SYNOPSIS
mdoc(7) police: Use the new .In macro for #include statements.
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.In sys/types.h
.In netinet/in.h
.In libutil.h
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Ft int
.Fn realhostname "char *host" "size_t hsize" "const struct in_addr *ip"
.Sh DESCRIPTION
The function
.Fn realhostname
converts
.Ar ip
Mechanically kill hard sentence breaks.
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to the corresponding host name.
This is done by resolving
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Ar ip
to a host name and then ensuring that the host name resolves
back to
.Ar ip .
.Pp
.Ar host
must point to a buffer of at least
.Ar hsize
bytes, and will always be written to by this function.
.Pp
Expand *n't contractions.
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If the name resolution does not work both ways or if the host name is longer
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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than
.Ar hsize
bytes,
.Xr inet_ntoa 3
is used to convert
.Ar ip
Correct spelling : ascii -> ASCII PR: docs/13702 Submitted by: Stephen J. Roznowski <sjr@home.com> Reviewed by: mpp
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to an ASCII form.
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Pp
If the string written to
.Ar host
is
.Ar hsize
bytes long,
.Ar host
will not be NUL terminated.
.Sh RETURN VALUES
The .Fn function
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The
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Fn realhostname
The .Fn function
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function will return one of the following constants which are defined in
mdoc(7): Properly mark C headers.
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.In libutil.h :
Add realhostname() - a function to correctly lookup a name by address and ensure that the name resolves back to the original address.
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.Pp
.Bl -tag -width XXX -offset XXX
.It Li HOSTNAME_FOUND
A valid host name was found.
.It Li HOSTNAME_INCORRECTNAME
A host name was found, but it did not resolve back to the passed
.Ar ip .
.Ar host
now contains the numeric value of
.Ar ip .
.It Li HOSTNAME_INVALIDADDR
.Ar ip
could not be resolved.
.Ar host
now contains the numeric value of
.Ar ip .
.It Li HOSTNAME_INVALIDNAME
A host name was found, but it could not be resolved back to any ip number.
.Ar host
now contains the numeric value of
.Ar ip .
.El
.Sh SEE ALSO
.Xr gethostbyaddr 3 ,
.Xr gethostbyname 3 ,
several tcp apps IPv6 update -inetd -rshd -rlogind -telnetd -rsh -rlogin Reviewed by: freebsd-arch, cvs-committers Obtained from: KAME project
2000-01-25 14:52:10 +00:00
.Xr inet_ntoa 3 ,
.Xr realhostname_sa 3
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